420 



BULLETIN No. 127. 



[August, 



like an undeveloped stem branching out toward the eyes. The re- 

 sults of their analyses of these parts, calculated to the fresh basis 

 are: 



COMPOSITION OF THE DIFFERENT ZONES OF THE POTATO TUBER 



The water and nitrogen contents increase as we go from the 

 outer to the inner zones, while the starch content decreases. It is 

 also interesting that the percent of proteid nitrogen to the total ni- 

 trogen decreases in the inner zones; the former being 68.7 percent 

 in the cortical layer, 56.0 percent in the outer medullary layer and 

 47.3 percent in the inner medullary layer. 



This work was believed to give a chemical basis for the selection 

 for planting, of tubers which were of better table quality. It should 

 be noted, however, that the standard for table quality in France is 

 decidedly different from that in the United States. The accepted 

 method of cooking there is frying in deep fat, for which a potato 

 which holds its form is desired ; while in this country probably nine- 

 tenths of the consumption is of boiled potatoes, which are desired 

 dry and mealy. Potatoes imported from Vilmorin, which I have 

 examiner! , r>^r1v all possessed a yellow flesh, a strong flavor, and 

 were firm and soggy after boiling. 



Shortly after the appearance of this work, Frisby and Bryant 

 (38) reported separations and analyses of these different zones in 

 the American variety "White Star," without separating the outer 

 and inner medullary layers, and found the following composition : 



Zone Water percent Proteid N. Total N. N. free extract 



Cortical layer 83.2 .24 .36 12.6 



Outer and inner Med 81.1 .18 .32 15.7 



*Probably total Nx6.25 although it is not stated. 



